In the oil and chemical process industries, various oleaginous and aqueous liquids and vapours are conveyed through pipes and tubes, sometimes at elevated temperatures and pressures, and sometimes the pipes and tubes may be left empty. During use, the insides of the pipes and tubes become encrusted with scale or carbonaceous deposits, or become rusty. The formation of such deposits of scale, carbonaceous material or rust can seriously restrict the flow through the pipes or tubes or reduce the rate of heat transfer through them.
Furthermore, with new pipes or tubes, it is necessary to clean the insides or otherwise treat them in order to render them fit for service. New pipes usually contain an adherent layer of mill scale due to the manufacturing process and problems will arise in service if the mill scale should become detached as it can clog and interfere with various instrumentalities with which the pipe or tube is used.
This is a particular problem with pipe, tubing and casing used in the oil recovery industry where the tubing or casing and the various instrumentalities are located undersea at depths of several hundred feet.